The use of polyethylene piping in gas, water and chemical industries can be attributed to its lightness, flexibility and good corrosion resistance, as well as the ease with which the polyethylene pipes can be joined. Joining is commonly performed using the butt fusion or butt welding method. The quality of butt fusion joints in polyethylene pipe systems depends primarily on control of process parameters during welding. Inspection methods are evidently required if one wants to objectively assess butt fusion joint quality.
At one stage a guideline standard (ASTM F600-78) for the manual ultrasonic inspection of butt fusion welds in polyethylene pipe was introduced, which standard was withdrawn again in 1991 for being too dependent on the skill of the operator.
In “Ultrasonic and Radiographic NDT of Butt Fusion Welds in Polyethylene Pipe”, NDTnet—April 1996, Vol. 1 No. 04, by I. J. Munns and G. A. Georgiou an ultrasonic Time of Fight Diffraction (ToFD) technique was presented for non-destructively inspecting butt fusion welds in polyethylene pipe systems.